Friends, neighbors, and especially NCIS fans, sit yourselves down because this is a story you’re going to want to hear. It’s a tale of love, of broken trust, of a friendship that reportedly came to an end over a dog bite.

This week, Pauley Perrette fired off three tweets that seemed to signal something darker than simple boredom had fueled her decision to leave NCIS after 15 seasons. Her tweets were vague, but they included phrases like “multiple physical assaults,” an allusion to a “machine” keeping her silent and the need to protect her crew, and the words, “He did it.” After her tweets garnered widespread attention, the actress added one more thought: “I want to thank my studio and network CBS They have always been so good to me and always had my back.” A source told the Wrap that the actress didn’t mean to imply that there has been physical abuse or sexual harassment on the set, but her tweets did spark discussion about an on-set dispute from a couple years ago.

In 2016, after more than a decade of appearing together on the CBS procedural, things reportedly turned icy between Perrette and her co-star Mark Harmon. The inciting incident? Harmon, who plays Jethro Gibbs, brought his dog to set. An unidentified crew member was playing with the dog, who reportedly bit him—causing an injury that requires 15 stitches, the Wrap reports. After that, insiders told the Wrap, Harmon continued to bring the dog to set. Harmon’s attorney, Barry Axelrod, told the Wrap that this was not the case, while one person familiar with the situation added, “If he brought the dog to work, he was on a leash or in his trailer. He definitely took steps to make sure that the dog was with him and was not just roaming freely, and then he just stopped bringing him altogether.”

Per the Wrap’s sources, some members of the NCIS cast and crew were uncomfortable with Harmon’s dog returning to the set but were reluctant to confront Harmon, who is also an executive producer on the series. Perrette, however, had the power to say something, thanks to her status as the show’s most beloved character, Abby Sciuto. And when she did, their rift reportedly began.

A source told the Wrap that an arrangement was quietly put in place to ensure that the two never had to film in the same location. When they did appear together in Perrette’s final season of NCIS, it was apparently a feat of TV editing magic: “She did her scenes on one day and he did his work on other days, and they still produced a great show,” the source said. “It was simply scheduled that they did not work the same days.”

This arrangement seems to explain why Gibbs and Abby have appeared in far fewer scenes together in recent seasons. Abby never even said goodbye to Gibbs in person during her farewell episode last week. However, a source made sure to clarify that the actress had already made her decision to leave the show before the alleged dog bite incident even happened.

When reached for comment, CBS pointed V.F. to its original statement following Perrette’s tweets: “Pauley Perrette had a terrific run on N.C.I.S. and we are all going to miss her. Over a year ago, Pauley came to us with a workplace concern. We took the matter seriously and worked with her to find a resolution. We are committed to a safe work environment on all our shows.”

Representatives for Harmon and Perrette did not immediately respond to V.F.’s request for comment.